With this proposal we want to study the (deuterated) hydration shell of facetted iron oxide nanoparticles (IONPs). IONPwater interfaces are of great importance for biomedical applications. Recently, we showed by X-ray PDF, that even 7 nm IONPs exhibit pronounced water ordering in the adsorbed water layer and beyond out to 15 Å. Thereby, we distinguished interatomic distances of adsorbed H2O at < 3 Å. Yet, questions regarding the interfacial hydrogen bond network remain. The higher sensitivity of neutrons towards H and D will allow to elucidate the contributions of surface O-D groups and ligands. Therefore, we aim to characterize the interfacial structure of dry and wet (protonated and deuteriated) IONP powders as well as the hydration shells in 0.5 wt% IONP dispersions. This proposal will shed light on the complex interplay of ligand, solvent and nanoparticle at colloidal interfaces.
